An integrative approach to define chemical exposure threshold limits for endangered sea turtles.

Environmental contaminants pose serious health threats to marine megafauna species, yet methods defining exposure threshold limits are lacking. Here, a three-pillar chemical risk assessment framework is presented based on (1) species- and chemical-specific lifetime bioaccumulation modelling, (2) non-destructive in vitro and in vivo toxicity threshold assessment, and (3) chemical risk quantification. We used the effects of cadmium (Cd) in green sea turtles (Chelonia mydas) as a proof of concept to evaluate the quantitative mechanistic modelling approach.

Simultaneous quantification of humic acid-water and silanized glass-water partition constants for PCBs, PCDDs and OCDF.

Super-hydrophobic organic contaminants (SHOCs) such as polychlorinated biphenyls (PCBs), polychlorinated dibenzo-p-dioxins (PCDDs) and octachlorodibenzofuran (OCDF) can sorb to dissolved hydrophobic materials including humic acids (HAs), enhancing their apparent aqueous solubility and potentially resulting in increased groundwater contamination and offsite transport. To manage risks associated with transport of and contamination by SHOCs, modelling approaches incorporating partitioning data, i.e.

Transport potential of super-hydrophobic organic contaminants in anionic-nonionic surfactant mixture micelles.

Surfactant mixtures are commonly used in agricultural and soil remediation applications, necessitating an understanding of their micellization behavior and associated impact on the fate of co-existing chemicals in the subsurface. A polymer-water sorption isotherm approach was shown to present an alternative to traditional methods for quantifying, understanding and predicting surfactant mixture properties. Micelle compositions were measured for anionic-nonionic surfactant mixtures.

PCDD/F and PCB levels in different tissues from dugongs (Dugong dugon) inhabiting the Queensland coastline.

Previous studies on PCDD/Fs and PCBs in dugong (Dugong dugon) blubber reported unexpectedly elevated TEQ levels. This study analysed archived blubber, muscle, liver and faeces obtained from dugongs from two areas along the Queensland coast. All samples showed detectable levels of PCDDs and PCBs, while PCDFs were consistently near or below LOQ.

Evaluating internal exposure of sea turtles as model species for identifying regional chemical threats in nearshore habitats of the Great Barrier Reef.

Marine megafauna that forage in proximity to land can be exposed to a diverse mixture of chemicals that - individually or combined - have the potential to affect their health. Characterizing such complex exposure and examining associations with health still poses considerable challenges. The present study summarizes the development and application of novel approaches to identifying chemical hazards and their potential impacts on the health of coastal wildlife, using green sea turtles as model species.

Multi-residue screening of non-polar hazardous chemicals in green turtle blood from different foraging regions of the Great Barrier Reef.

Green turtles spend a large part of their lifecycle foraging in nearshore seagrass habitats, which are often in close proximity to sources of anthropogenic contaminants. As most biomonitoring studies focus on a limited number of targeted chemical groups, this study was designed to screen for a wider range of hazardous chemicals that may not have been considered in prior studies. Whole blood of sub-adult green turtles (Chelonia mydas) were sampled from three different locations, a remote, offshore 'control' site; and two coastal 'case' sites influenced by urban and agricultural activities on the Great Barrier Reef in North Queensland, Australia.

Elucidating temporal trends in trace element exposure of green turtles (Chelonia mydas) using the toxicokinetic differences of blood and scute samples.

Blood is considered a suitable biomonitoring matrix for evaluating relatively recent exposure to environmental contaminants since abrupt changes in exposure regimes are rapidly reflected in blood. On the other hand, keratinized tissues, such as turtle scutes, are known to integrate trace element exposure over relatively long time periods. This study aimed to test the use of the differences in blood and scute to inform on the historical trace element exposure of green turtles.

Effect of surfactant application practices on the vertical transport potential of hydrophobic pesticides in agrosystems.

Surfactants have the potential to modify the environmental behavior of hydrophobic pesticides leading to an enhanced or reduced mobility risk. This risk is often overlooked in registration procedures due to a lack of suitable methodologies to quantify the transport potential of pesticides with surfactants. In this study we present a novel methodology designed to study the surfactant facilitated transport of pesticides under controlled equilibrium and dynamic hydrologic conditions.

Effect-based approach for screening of chemical mixtures in whole blood of green turtles from the Great Barrier Reef.

Organisms are exposed to mixtures of both known and unknown chemicals which are diverse and variable, and thus difficult and costly to characterise and monitor using traditional target analyses. The objective of this study was to validate and apply in vitro effect-based methods by which whole blood can be used to screen internal exposure to such complex chemical mixtures. For this study, we used whole blood of green sea turtles (Chelonia mydas).

Non-targeted, high resolution mass spectrometry strategy for simultaneous monitoring of xenobiotics and endogenous compounds in green sea turtles on the Great Barrier Reef.

Chemical contamination poses a threat to ecosystem, biota and human health, and identifying these hazards is a complex challenge. Traditional hazard identification relies on a priori-defined targets of limited chemical scope, and is generally inappropriate for exploratory studies such as explaining toxicological effects in environmental systems. Here we present a non-target high resolution mass spectrometry environmental monitoring study with multivariate statistical analysis to simultaneously detect biomarkers of exposure (e.

Medium-Chain Chlorinated Paraffins (CPs) Dominate in Australian Sewage Sludge.

To simultaneously quantify and profile the complex mixture of short-, median-, and long-chain CPs (SCCPs, MCCPs, and LCCPs) in Australian sewage sludge, we applied and further validated a recently developed novel instrumental technique, using quadrupole time-of-flight high resolution mass spectrometry running in the negative atmospheric pressure chemical ionization mode (APCI-qTOF-HRMS). Without using an analytical column the cleaned extracts were directly injected into the qTOF-HRMS followed by quantification of the CPs by a mathematical algorithm. The recoveries of the four SCCP, MCCP and LCCP-spiked sewage sludge samples ranged from 86 to 123%.

Trace element reference intervals in the blood of healthy green sea turtles to evaluate exposure of coastal populations.

Exposure to essential and non-essential elements may be elevated for green sea turtles (Chelonia mydas) that forage close to shore. Biomonitoring of trace elements in turtle blood can identify temporal trends over repeated sampling events, but any interpretation of potential health risks due to an elevated exposure first requires a comparison against a baseline. This study aims to use clinical reference interval (RI) methods to produce exposure baseline limits for essential and non-essential elements (Na, Mg, K, Ca, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, As, Se, Mo, Cd, Sb, Ba, and Pb) using blood from healthy subadult turtles foraging in a remote and offshore part of the Great Barrier Reef.

Chlorinated paraffins in the environment: A review on their production, fate, levels and trends between 2010 and 2015.

This review provides an update on information regarding the production volumes, regulations, as well as the environmental levels, trends, fate and human exposure to chlorinated paraffin mixtures (CPs). CPs encompas thousands congeners with varying properties and environmental fate. Based on their carbon chain lengths, CPs are divided into short- (SCCPs; C10-13), medium- (MCCPs; C14-17) and long- (LCCPs; C ≥ 18) chained groups.

Solubility enhancement of dioxins and PCBs by surfactant monomers and micelles quantified with polymer depletion techniques.

Partitioning of super-hydrophobic organic contaminants (SHOCs) to dissolved or colloidal materials such as surfactants can alter their behaviour by enhancing apparent aqueous solubility. Relevant partition constants are, however, challenging to quantify with reasonable accuracy. Partition constants to colloidal surfactants can be measured by introducing a polymer (PDMS) as third phase with known PDMS-water partition constant in combination with the mass balance approach.

Screening of organic and metal contaminants in Australian humpback dolphins (Sousa sahulensis) inhabiting an urbanised embayment.

As a marine mammal species that inhabits shallow nearshore waters, humpback dolphins are likely exposed to a wide range of pollutants from adjacent land-based activities. Increased mortality rates of Australian humpback dolphins (Sousa sahulensis) in waters off a major urbanised centre triggered investigations into the threats to these species, including their contaminant exposure. The present study utilised archived tissues from 6 stranded animals to screen for a range of pollutants (PCDD/Fs, PBDEs, PCBs, organochlorine pesticides, PAHs, organotins, essential and non-essential elements) to inform future biopsy based biomonitoring strategies.

Experimental Solubility Approach to Determine PDMS-Water Partition Constants and PDMS Activity Coefficients.

Freely dissolved aqueous concentration and chemical activity are important determinants of contaminant transport, fate, and toxic potential. Both parameters are commonly quantified using Solid Phase Micro-Extraction (SPME) based on a sorptive polymer such as polydimethylsiloxane (PDMS). This method requires the PDMS-water partition constants, KPDMSw, or activity coefficient to be known.

Coupling passive sampling with in vitro bioassays and chemical analysis to understand combined effects of bioaccumulative chemicals in blood of marine turtles.

Conventional target analysis of biological samples such as blood limits our ability to understand mixture effects of chemicals. This study aimed to establish a rapid passive sampling technique using the polymer polydimethylsiloxane (PDMS) for exhaustive extraction of mixtures of neutral organic chemicals accumulated in blood of green turtles, in preparation for screening in in vitro bioassays. We designed a PDMS-blood partitioning system based on the partition coefficients of chemicals between PDMS and major blood components.

Recent developments in capabilities for analysing chlorinated paraffins in environmental matrices: A review.

Concerns about the high production volumes, persistency, bioaccumulation potential and toxicity of chlorinated paraffin (CP) mixtures, especially short-chain CPs (SCCPs), are rising. However, information on their levels and fate in the environment is still insufficient, impeding international classifications and regulations. This knowledge gap is mainly due to the difficulties that arise with CP analysis, in particular the chromatographic separation within CPs and between CPs and other compounds.

Isomer-specific investigation of PCDD/F mobility and other fate processes in deep soil cores.

Polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) are highly hydrophobic compounds with low migration potential in soil-water. Nevertheless, they have been occasionally reported in subsurface soils hypothesised as the result of facilitated transport processes with colloids or surfactants, or yet unidentified in-situ formation processes. To date, however, the prevalence of deep soil contamination, involved processes and their kinetics remain poorly understood.

Adaptive stress response pathways induced by environmental mixtures of bioaccumulative chemicals in dugongs.

To address the poorly understood mixture effects of chemicals in the marine mammal dugong, we coupled equilibrium-based passive sampling in blubber to a range of in vitro bioassays for screening mixtures of bioaccumulative chemicals. The modes of action included early effect indicators along important toxicity pathways, such as induction of xenobiotic metabolism, and some integrative indicators downstream of the molecular initiating event, such as adaptive stress responses. Activation of aryl hydrocarbon receptor (AhR) and Nrf2-mediated oxidative stress response were found to be the most prominent effects, while the p53-mediated DNA damage response and NF-κB-mediated response to inflammation were not significantly affected.

Levels of arsenic, cadmium, lead and mercury in the branchial plate and muscle tissue of mobulid rays.

Mobulid rays are targeted in fisheries for their branchial plates, for use in Chinese medicine. Branchial plate and muscle tissue from Mobula japanica were collected from fish markets in Sri Lanka, and muscle tissue biopsies from Manta alfredi in Australia. These were analysed for arsenic, cadmium, lead and mercury and compared to maximum levels (MLs) set by Food Standards Australia and New Zealand (FSANZ), European Commission (EC) and Codex Alimentarius Commission.

A multi-element screening method to identify metal targets for blood biomonitoring in green sea turtles (Chelonia mydas).

Biomonitoring of blood is commonly used to identify and quantify occupational or environmental exposure to chemical contaminants. Increasingly, this technique has been applied to wildlife contaminant monitoring, including for green turtles, allowing for the non-lethal evaluation of chemical exposure in their nearshore environment. The sources, composition, bioavailability and toxicity of metals in the marine environment are, however, often unknown and influenced by numerous biotic and abiotic factors.

Historical emissions of octachlorodibenzodioxin in a watershed in Queensland, Australia: estimation from field data and an environmental fate model.

An octachlorodibenzodioxin (OCDD)-dominated contamination is present along the coast of Queensland, Australia. Several findings indicate that this contamination originates from pesticide use, although due to limited information on OCDD levels in the pesticides used, estimating past and current emissions of OCDD solely from pesticide use data is unfeasible. We used all the qualitative and quantitative information available on OCDD in pesticides together with a previously validated chemical fate model for a catchment in the Queensland Wet Tropics to back-calculate the emissions of OCDD from measured soil concentrations.

Clinical and Pathological Findings in Green Turtles (Chelonia mydas) from Gladstone, Queensland: Investigations of a Stranding Epidemic.

An investigation into the health of green turtles was undertaken near Gladstone, Queensland, in response to a dramatic increase in stranding numbers in the first half of 2011. A total of 56 live turtles were subject to clinical examination and blood sampling for routine blood profiles, and 12 deceased turtles underwent a thorough necropsy examination. This population of green turtles was found to be in poor body condition and a range of infectious and non-infectious conditions were identified in the unhealthy turtles, including hepato-renal insufficiency (up to 81%, 27/33 based on clinical pathology), cachexia (92%, 11/12), parasitism (75%, 9/12), cardiopulmonary anomalies (42%, 5/12), gastroenteritis (25%, 3/12), masses (25%, 3/12) and mechanical impediments (17%, 2/12 based on necropsy).